It is not a question of rights, it is a question of common courtesy.
It is courteous to ask, and if refused, to respect their choice, after all it is their property.

Put yourself in their shoes. Do you really want photos of your garden used in some company's publicity work? Perhaps you do or perhaps you don't mind but you would definitely expect them to ask first, as a matter of respect and courtesy.

William Pitt (in 1760) said "The poorest man may in his cottage bid defiance to all the force of the Crown. It may be frail, its roof may shake, the wind may blow through it. The rain may enter. The storms may enter. But the king of England may not enter. All his forces dare not cross the threshold of the ruined tenement."